Abstract ID: 28.7396 | Accepted as Talk | Talk/Oral | 2025-02-27 17:15 - 17:30 | Ágnes‐Heller‐Haus/Small Lecture Room

The Patagonian ice masses are experiencing one of the highest rates of mass loss on the planet. The primary contributors to sea level rise are the Northern and Southern Patagonian Ice Fields. The Southern Patagonian Ice Field is characterised by the presence of large outlet glaciers that terminate in either fjords or proglacial lakes. These outlet glaciers are both the largest and the main contributors to the aforementioned mass loss. However, it is important to note that glacier retreat exhibits considerable spatial variability. Perito Moreno Glacier, a prominent glacier in the region, has frequently been reported as one of the last glaciers to defy global warming, appearing unaffected by climate change as adjacent glacier basins recede. The bedrock topography of water-terminating glaciers is known to have a significant impact on their climate sensitivity, a factor which is largely unknown in the case of Glaciar Perito Moreno. On March 19 and 23, 2022, we conducted a new ice thickness survey at Glaciar Perito Moreno ice thickness using a helicopter-borne 25 MHz ground penetrating radar system. The proglacial lake bed was bathymetrically surveyed on March 30, 2023. These measurements were then incorporated into an established ice thickness reconstruction approach to derive the bedrock topography of the entire glacier domain. Furthermore, we analysed a time series of ice surface elevation and velocity changes from bistatic radar interferometry based on SRTM, TanDEM-X imagery, and ITS_Live data. We observe an acceleration of glacier surface elevation decrease in the lower regions from 0.34 m a-1 (2000-2019) to up to 5.5 m a-1 (2019-2024), with corresponding glacier acceleration on the tongue and unprecedented frontal retreat of several hundred meters in the northern and eastern glacier margins. We then extended the current surface lowering rates in a simplistic numerical model and found a high potential for a large-scale buoyancy-driven glacier retreat of several kilometres once the glacier decouples from a bedrock ridge. The high susceptibility of Perito Moreno to surface lowering follows a pattern similar to that of other lacustrine calving glaciers in Patagonia in recent decades.